7048

• UCREFRP Catalog Number: 7048
• Author: Desert Fishes Council ‎(Edwin Pister, e.
• Title: Proceedings of the Desert Fishes Council
• USFW Year: 1991.
• USFW - Doc Type: Volumes XX and XXI
• Copyright Material: NO

GEOHYDROLOGIC EVIDENCE FOR THE DEVELOPMENT OF DEVILS HOLE, SOUTHERN NEVADA
AS AN AQUATIC ENVIRONMENT
by Alan C. Riggs
ABSTRACT
Devils Hole apparently results from the tectonic pull-apart of a small
fault in Paleozoic carbonate bedrock. It presently extends from ground
surface, through the water table 16 m down, to a depth of at least 100 m.
The fault started to open at depth at least 750 Ka ago, but did not reach
the surface until later. The early water table was high, filling the
spreading fissure with ground water supersaturated with respect to calcite.
Travertine, a distinctive morph of calcite, precipitated on all underwater
surfaces. Over time, as water table fluctuated and slowly fell to its
present level, a different calcite morph precipitated at water level. The
distinctiveness of the two morphs and their suitability for Uranium-series
dating allow us to begin interpreting the history of Devils Hole in terms of
its suitability for habitation by the Devils Hole pupfish, Cyprinodon
diabolis.
There is probably no evidence of initial habitation of Devils Hole by C.
diabolis; the best we can do is to fix the time when Devils Hole first
became an isolated habitat suitable for pupfish. Two possible scenarios
are: 1) roof collapse prior to the last excursion of water table above
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